For the binder for refractories for the inner liners of industrial kilns of various high temperature processes such as the steelmaking process, sodium phosphate, sodium silicate, furan resin, phenol resin, pitch, aluminum lactate, sodium aluminate, silica sol, alumina sol, polyvinyl alcohol, methyl cellulose, carboxymethyl cellulose, ethyl silicate, alumina cement, hydraulic alumina, and numerous other inorganic and organic compounds are being used.
In recent years, in the field of refractories, due to improvements in installation ability, ease of repair, etc., increased use is being made of monolithic refractories. Monolithic refractories are now being widely used even at locations contacting molten iron or high temperature slag where shaped bricks were previously used.
In the production of monolithic refractories, high pressure press operations such as seen in the production of shaped refractories are not performed. Therefore, the importance of the characteristics of the material or binders is high. Among these, alumina cement (main constituent compound: CaO.Al2O3, CaO.2Al2O3, 12CaO.7Al2O3) is being used for broad applications as a binder for refractories for troughs, ladles, tundishes, etc.
Furthermore, alumina-type binders including ingredients other than CaO—Al2O3 are also being studied. For example, Japanese Patent Publication (A) No. 52-148524 and Japanese Patent Publication (A) No. 58-26079 disclose a mixture of materials for producing refractory alumina cement mainly comprised of barium or strontium and alumina. Specifically, by suitably heat treating a mixture of carbonates and chlorates, a mixture of materials for producing cement is obtained.
Further, the Journal of the Ceramic Society of Japan (89, 10, 572-577, 1981, Ito et al.) discloses to add to a CaO—SrO—Al2O3-based cement a commercially available high purity reagent and to mix and fire the same to prepare a prototype binder and shows the property of hardening by the addition of water.